Stopping traffic.
D000818:Animals; D000835:Animals, Wild; D003132:Commerce; D003247:Conservation of Natural Resources; D004777:Environment; D004787:Environmental Pollution / Q000517:prevention & control*; D015386:Hazardous Substances; D006801:Humans; D010944:Plants; D011050:Policy Making; D014480:United Nations
D015386:Hazardous Substances